Slide valves



June 24, 1969 c, N-r 3,451,426

suns VALVES Filed Oct. 12. 1966 Sheet 4 43 58 '1 1K 0 Q 4; x s 55 INVENTOR JOHN C. E. FLINT BY A /Mw,ffi%

ATTORNEYS J. C. E. FLINT June 24, 1969 SLIDE VALVES SheetiofS Filed Oct. 12, 1966 INVENTOR JOHN 6 5 Fl/NT ATTORNEYS June 24, 1969 J. c. E. FLINT 3,451,426

SLIDE VALVES Filed Oct. 12, 1966 Sheet 5 0f 5 INVENTOR :ro w CE. FZ/MT ATTORNEYS J. C. E. FLINT June 24, 1969 SLIDE VALVES Sheet Filed Oct. 12, 1966 R O N T4 R N 0 E 2 f W0 A w.

J. C. E. FLINT June 24, 1969 SLIDE VALVES Sheet Filed Oct. 12, 1966 INVENTOR United States Patent 3,451,426 SLIDE VALVES John C. E. Flint, Chalford, England, assignor to Dowty Technical Developments Limited, Cheltenham, England, a British company Filed Oct. 12, 1966, Ser. No. 586,208 Claims priority, application Great Britain, Oct. 19, 1965, 44,145/ 65 Int. Cl. F17d 3/ 02, 3/00 US. Cl. 137-59613 Claims ABSTRACT OF THE DISCLOSURE sliders.

This invention relates to slide valves which term is intended to include valves in which the displaceable members are slidable in linear or in arcuate manner.

According to this invention a slide valve includes a casing with at least two displaceable members housed for sliding displacement in the casing away from a neutral position. A single inlet connection and a single exhaust connection are formed in the casing, and at least one service port is provided in the casing respectively in association with each member. Pressure fluid can be directed to each service port by the respective displaceable member in dependence upon its movement away from said neutral position. The casing has a by-pass passage for directly placing the single inlet connection in communication with the single exhaust connection. A single unloader valve, positioned in said by-pass passage, is operable by mechanical means associated with all the members when any one of the members is moved away from its neutral position, to close the by-pass passage.

Thus, when the or all of the displaceable members are in their neutral positions, the unloader valve is open so that fluid supplied to the inlet connection is passed directly to the exhaust connection, by-passing the or each displaceable member. When the or any one of the displaceable members is moved away from the neutral position, the mechanical means is operative to close the unloader valve, whereupon supply fluid is directed to the or each displaceable member, so as to be available for direction by the or each member to a service or services to which the service ports are connectible.

The mechanical means may include a cam, formed upon the or each displaceable member, engaged by a respective follower carried upon or formed by a single rod member, itself passing through the casing transversely with respect to the displaceable member or members. The unloader valve may be provided at one end portion of the casing and its displaceable element be engaged by a part of said means. The rod member may be supported at both end portions upon swinging levers Whose pivotal axes are coincident and also parallel with the rod memher, so that when the or any one of the displaceable members is moved away from its neutral position, the cam causes the rod member to swing about the pivotal axes of the levers in such a manner as to displace the displaceable element of the unloader valve towards its closed position.

3,451,426 Patented June 24, 1969 Spring means may be provided biassing the displaceable element towards its closed position. Further, the rod member, together with the followers, may be spring-urged in the cam-engaging direction.

The or each displaceable member may be slidable linearly in the casing and be of rectangular cross-section in a plane at right-angles to its direction of sliding. Such a displaceable member may have said cam formed on one longitudinal edge thereof.

One embodiment of the invention will now be particularly described by way of example with reference to the accompanying drawings of which,

FIGURE 1 is a diagrammatic plan view of a multiple slide valve unit,

FIGURE 2 is an enlarged cross-section taken along the line IIII on FIGURE 1,

FIGURE 3 is an enlarged cross-section taken along the line III-III on FIGURE 1,

FIGURES 4 and 6 are views similar to that of FIG- URE 2 but in different operating conditions of the multiple slide valve unit, and,

FIGURES 5 and 7 are views similar to that of FIG URE 3 but in the different operating conditions of FIG- URES 4 and 6 respectively.

Referring to the drawings a multiple slide valve unit 11 comprises seven casing plates 12, 1.3, 14, 15, 16, 17 and 18, interspaced one from the other by six slider frames 19, 20, 21, 22, 23 and 24. As shown more clearly in FIGURES 2 to 7, each slider frame incorporates a chamber 25 of such shape as to provide a linear slide for a ported slider 26 constituting a displaceable valve member. Each slider is of rectangular cross-section in a plane' at right-angles to its direction of sliding and is controllable by means of a respective pivoted lever 27 mounted externally of the casing assembly. Spring centering means 28 are provided for biassing each slider to its neutral position, each means 28 being cooperable with a control rod 29 itself pivotally connected to a respective lever 27. Each control rod is coupled to its respective slider by means of a tongue-and-slot connection 30.

The casing plates 12 to 18 and the slider frames 19 to 24 are held in sealing engagement in banked manner by means of bolts which pass through suitable apertures formed in these components.

The casing plate 12 at one end portion of the banked assembly is provided with an inlet connection 31 common to the entire assembly and connectible to a source of liquid under pressure, while the casing plate 18 at the opposite end portion of the assembly is provided with an exhaust or drain connection 32, also common to the entire assembly.

Aligned ports 33, 34 are provided in the casing plates and slider frames thereby to form a pressure liquid feeder passage running the length of the bank and in communication with the inlet connection 31. This passage is also in communication with the drain connection 32 through a suitable relief valve (not shown) incorporated in the drain casing plate 18-. Branch passageways 35 are respectively taken from the passage 33/34 and lead through the casing plates respectively to each of the sliders 26, the sliders themselves having webbed slots 36 cut therethrough and elongated in the direction of sliding for receiving pressure liquid both when the sliders are in their neutral positions and when in their operative positions. The branch passageways 35 each incorporate a check valve (not shown) to prevent reverse flow of liquid towards the inlet connection 31.

The chambers 25 in which the sliders are mounted are placed in communication with the drain connection 32 so that both end portions of each slider 26 are subject to drain conditions.

An unloader valve 37 is provided in the inlet casing plate 12, the displaceable element 38 of this valve having two lands 39 and 40, between which is formed an annular recess 41. This unloader valve is so positioned in relation to the pressure liquid feeder passage 33, 34 running the length of the bank, as, when open, to provide direct communication between the inlet connection 31 and the drain connection 32, but when closed to block such communication. A coil spring 42 is provided to bias the element 38 towards its closed position. In the closed position the land 39 of the element 38 closes over an annular opening 43 itself in communication with drain through a port 44.

Each of the sliders 26 have balance porting 45, 46, and are of the four-way type so that a service S associated therewith, which takes the form of a telescopic jack, is operable in double-acting manner. When the slider 26 is moved away from its neutral position to the left in FIG- URES 2, 4 and 6 of the drawings, it permits pressure liquid passing through the respective branch passageway and its associated check valve from the feeder passage 33, 34 and available in the elongated slot 36 in the slider 26, to pass from this slot out through a service port 47 in the associated casing plate, piping 48 being taken therefrom to the left-hand side of the telescopic jack S. At the same time liquid on the other side of the jack is exhausted to return through further piping 49 which opens into a further service port 50 in the said associated casing plate, this port being opened by the straight end edge 51 of the slider 26 so that flow of liquid occurs into the chamber 52 at the right-hand end of the slider frame from where it passes through passageways (not shown) to the drain connection 32.

When the slider is moved back to its neutral position,

the service S is held hydraulically locked in the selected position, but as soon as the slider is moved from its neutral position to the right in FIGURES 2, 4 and 6 of the drawings, the double-acting jack S operates in converse manner, flow occurring to the jack S through the port 50 and pipe 49, and liquid exhausting from the jack through pipe 48 and port 47, the straight end edge 51 of the slider opening the port 47 to the chamber 52'.

Each slider 26 is provided with a cam 53 formed on its lower longitudinal edge as shown in FIGURES 2, 4 and 6, the same edge for all the sliders. All the cams 53 have similar characteristics and each have a follower 54 maintained in engagement therewith. All the followers 54 are mounted upon a rod member 55 which passes transversely of the sliders along the length of the bank. The end portions of the rod member 55 are supported by swinging levers, one of which is shown at 56, themselves keyed upon a further rod member 57 mounted in suitable bearings (not shown) within the casing, the axis of this further rod member lying parallel with the axis of the first rod member 55.

Fast with the further rod member 57 is a further lever 58 which engages the annular recess 41 formed between the two lands 39 and 40 of the unloader valve element 38. A light coil spring 59 connected to this lever 58 serves to maintain the followers 54 in engagement with the respective cams 53.

All of the cams are generally of inverted shallow V- shape and it is so arranged that when all of the sliders 26 are in their neutral positions as shown in FIGURES 2 and 3, the followers 54, rod members 55 and 57 and further lever 58 hold the displaceable element 38 of the unloader valve 37 in its open position so that there is direct communication between the inlet connection 31 of the valve block and the drain connection 32 by way of port 33, annular opening 43 and port 44.

In this way the sliders 26 and the relief valve (not shown) in the drain casing plate 18 are by-passed, so that no excessive heat is generated when the operation of the services associated with the respective sliders is not required.

When any one of the sliders 26 is moved away from its neutral position, however, the respective cam follower 54 rides up a rapid-action part 5311 of the cam profile 53, the unloader valve element 38 at the same time moving quickly, assisted by its coil spring 42, to a position as shown in FIGURE 5 where only a metering slot area defined by the cut-away portions 39a of the land 39 is presented to the supply flow. In this way, pressure is quickly raised in the branch passageways 35 to all of the sliders 26 because the feeder passageway 33, 34 between the inlet connection 31 and drain connection 32 is substantially blocked. As the slider 26 is moved further towards its fully operative position, the respective follower 54 rides along a slow-action part 5312 of the cam profile 53 as shown in FIGURE 4, thereby diverting flow at pressure from the feeder passage 33, 34 to the appropriate service port 47 or 50, in dependence upon the direction of movement of the slider. By virtue of the metering slot area 39a, diversion of flow is relatively gradual thereby affording good inching characteristics of the unloader valve.

Passage means 60 are provided communicating the feeder passage 33, 34 with a chamber 61 to the right in FIGURES 3, 5 and 7 of the land 40 of the unloader valve element 38. This passage means incorporates an orifice 62, thus under these conditions to ensure that the pressures on both sides of the unloader valve 37 are substantially equalised.

As the slider 26 nears the end of its travel, and thus the cam follower 54 has reached the end of the slowaction part of the cam profile 53 as shown in FIGURE 6, the metering area 39a of the unloader valve 37 having now been completely closed to supply, a final further rapidaction part 53c of the cam 53 elfectively causes movement of the unloader valve to a point where as shown in FIG- URE 7 there is positive sealing between the effective land 39 of the unloader valve and the casing across the opening 43, so that the required pressure liquid is now directed to the service being operated.

When the slider is moved back towards its neutral position, converse operation occurs, again with good inching characteristics.

As the slider is moved in the opposite direction away from its neutral position, the associated service S operates in the converse manner.

The invention obviates the use of conventional opencentre passageways which require additional porting in the sliders themselves. In consequence the size of the sliders is somewhat reduced and this results in a less bulky valve unit.

Also, with slide valves of the open-centre passageway type the slider must first traverse the open-centre passageway before pressure can be raised for supplying the respective service. In consequence, pressure is raised rather late in the travel of the slider, giving a large dead band and the subsequent inching is correspondingly abrupt. By the present invention such dead band is avoided and inching is improved.

Further, with open-centre passageways, the open-centre path upstream of the point of flow cut-off is pressurised and thus leakage occurs at each upstream intersection between the open-centre path and the sliders. Such disadvantage is not evident in constructions in accordance with the present invention.

The invention is in no way limited to slide valves in which the sliders are of rectangular cross-sectional shape, as in other embodiments the invention is with advantage applied to slide valves having sliders of other type. For example, the sliders may be of spool-type. Again, the sliders may be rotatable, or angularly adjustable, about a fixed rotational axis, and thus slidable in arcuate manner between opposed fiat surfaces formed on the interior of the slide valve casing.

In other embodiments, a slide valve block may be provided with any other desired multiplicity of members of sliders appropriate to the number of services to be controlled by the block.

Further, although in the first embodiment the services controlled take the form of double-acting hydraulic jacks, in other embodiments the services controlled may be single-acting jacks, reversible and non-reversible rotary hydraulic motors, and similar devices, the slider porting being arranged accordingly.

Again, although the mechanical means for effecting operation of the unloader valve comprises a cam-and-follower mechanism combined with a common rod member and swinging levers, in other embodiments other forms of transmisison between the sliders and the unloader valve, so arranged to effect closure of the unloader valve when one of the sliders is moved away from its neutral position, can alternatively be provided.

The invention is in no way limited to slide valves for liquids, as in other embodiments it is applied to slide valves intended for use in pneumatic or other gaseous systems.

I claim as my invention:

1. A slide valve including a casing, at least two displaceable members housed for sliding displacement in the casing away from a neutral position, a single inlet connection and a single exhaust connection formed in the casing, and at least one service port associated with each member, to which pressure fluid can be directed by the respective displaceable member in dependence upon its movement away from said neutral position, the casing having a by-pass for directly placing the single inlet connection in communication with the single exhaust connection, and a single unloader valve, positioned in said by-pass passage, which is operable by mechanical means associated with all the members when any one of the members is moved away from its neutral position to close the by-pass passage.

2. A slide valve as claimed in claim 1, wherein the mechanical means includes a cam, formed upon each displaceable member, engaged by a respective follower carried upon a single rod member.

3. A slide valve as claimed in claim 2, wherein said single rod member itself passes through the casing transversely with respect to the displaceable member or members.

4. A slide valve as claimed in claim 2, wherein the rod member, together with the followers, are spring-urged in the cam-engaging direction.

5. A slide valve as claimed in claim 2, wherein each displaceable member is slidable linearly in the casing.

6. A slide valve as claimed in claim 5, wherein each displaceable member is of rectangular cross-section in planes at right-angles to its direction of sliding.

7. A slide valve as claimed in claim 6, wherein each displaceable member has said cam formed on one longitudinal edge thereof.

8. A slide valve as claimed in claim 2, wherein each cam is of generally shallow Vsh-ape.

9. A slide valve as claimed in claim 8, whereon on both sides of the V, taken from the neutral position, the cam is provided firstly with a rapid-action profile portion followed by a slow-action profile portion and finally a further rapid-action profile portion.

10. A slide valve as claimed in claim 1, wherein the unloader valve is provided at one end portion of the cas ing and its displaceable element is engaged by a part of said means.

11. A slide valve as claimed in claim 10, wherein the rod member is supported at both end portions upon swinging levers.

12. A slide valve as claimed in claim 11, wherein the pivotal axes, of said swinging levers are coincident and also parallel with the rod member, so that, when any one of the displaceable members is moved away from its neutral position, the cam causes the rod member to swing about the pivotal axes of the levers in such a manner as to displace the displaceable element of the unloader valve towards its closed position.

13. A slide valve as claimed in claim 10, wherein spring means are provided which bias the displaceable element towards its closed position.

14. A slide valve as claimed in claim 10, wherein the displaceable element of the unloader valve is a spool having two lands, an annulus formed between the lands being engaged by a further lever fast with a further rod member which supports the swinging levers, so that dis placement or" the first rod member by said cam rocks the further rod member and said further lever, thereby to adjust said spool.

15. A slide valve as claimed in claim 14, wherein a first one of said lands is co-operable lWlth an annular opening in the casing, said annular opening when uncovered by said land placing the by-pass passage in its open condition.

16. A slide valve as claimed in claim 15, wherein metering slots are provided in the face of said first land remote from the other land to afford good inching characteristics in operation of the unloader valve.

17. A slide valve as claimed in claim 15, wherein passage means are provided to place that portion of said bypass passage upstream of the unloader valve in communication with that end portion of the displaceable element of the unloader valve remote 'from said first land.

18. A slide valve as claimed in claim 17, wherein a restrictor is provided in said passage means.

'19. A slide valve including a casing, at least one displaceable member housed for sliding displacement in the casing away from a neutral position, an inlet connection and an exhaust connection formed in the casing, and at least one service port associated with each member, to which pressure fluid can be directed by a respective displaceable member in dependence upon its movement away from said neutral position, the casing having a bypass passage for directly placing the inlet connection in communication with the exhaust connection, and an unloader valve, positioned in said by-pass passage, which is operable by mechanical means when any one of the members is moved away from its neutral position, to close the by-pass passage, the mechanical means including a cam, formed upon each displaceable member, engaged by a respective follower carried upon a single rod member.

20. A slide valve including a casing, at least one displaceable member housed for sliding displacement in the casing away from a neutral position, an inlet connection and an exhaust connection formed in the casing, and at least one service port associated with each member, to which pressure fluid can be directed by a respective displaceable member in dependence upon its movement away from said neutral position, the casing having a bypass passage for directly placing the inlet connection in communication with the exhaust connection, and an unloader valve, positioned in said by-pass passage, which is operable by mechanical means when any one of the members is moved away from its neutral position, to close the bypass passage, the unloader valve being provided at one end portion of the casing and its displaceable element being engaged by a part of said means.

References Cited UNITED STATES PATENTS 2,729,241 1/1956 Clark 137-596.12

BILLY J. WILHITE, Primary Examiner. R. 1. SMITH, Assistant Examiner. 

